Concerted roles of LRRTM1 and SynCAM 1 in organizing prefrontal cortex synapses and cognitive functions

Multiple trans-synaptic complexes organize synapse development, yet their roles in the mature brain and cooperation remain unclear. We analyzed the postsynaptic adhesion protein LRRTM1 in the prefrontal cortex (PFC), a region relevant to cognition and disorders. LRRTM1 knockout (KO) mice had fewer synapses, and we asked whether other synapse organizers counteract further loss. This determined that the immunoglobulin family member SynCAM 1 controls synapse number in PFC and was upregulated upon LRRTM1 loss. Combined LRRTM1 and SynCAM 1 deletion substantially lowered dendritic spine number in PFC, but not hippocampus, more than the sum of single KO impairments. Their cooperation extended presynaptically, and puncta of Neurexins, LRRTM1 partners, were less abundant in double KO (DKO) PFC. Electrophysiology and fMRI demonstrated aberrant neuronal activity in DKO mice. Further, DKO mice were impaired in social interactions and cognitive tasks. Our results reveal concerted roles of LRRTM1 and SynCAM 1 across synaptic, network, and behavioral domains.

Three-dimensional adaptive optical nanoscopy for thick specimen imaging at sub-50-nm resolution

Understanding cellular organization demands the best possible spatial resolution in all three dimensions. In fluorescence microscopy, this is achieved by 4Pi nanoscopy methods that combine the concepts of using two opposing objectives for optimal diffraction-limited 3D resolution with switching fluorescent molecules between bright and dark states to break the diffraction limit. However, optical aberrations have limited these nanoscopes to thin samples and prevented their application in thick specimens. Here we have developed an improved iso-stimulated emission depletion nanoscope, which uses an advanced adaptive optics strategy to achieve sub-50-nm isotropic resolution of structures such as neuronal synapses and ring canals previously inaccessible in tissue. The adaptive optics scheme presented in this work is generally applicable to any microscope with a similar beam path geometry involving two opposing objectives to optimize resolution when imaging deep in aberrating specimens.

Synaptic recognition molecules in development and disease

Synaptic connectivity patterns underlie brain functions. How recognition molecules control where and when neurons form synapses with each other, therefore, is a fundamental question of cellular neuroscience. This chapter delineates adhesion and signaling complexes as well as secreted factors that contribute to synaptic partner recognition in the vertebrate brain. The sections follow a developmental perspective and discuss how recognition molecules (1) guide initial synaptic wiring, (2) provide for the rejection of incorrect partner choices, (3) contribute to synapse specification, and (4) support the removal of inappropriate synapses once formed. These processes involve a rich repertoire of molecular players and key protein families are described, notably the Cadherin and immunoglobulin superfamilies, Semaphorins/Plexins, Leucine-rich repeat containing proteins, and Neurexins and their binding partners. Molecular themes that diversify these recognition systems are defined and highlighted throughout the text, including the neuron-type specific expression and combinatorial action of recognition factors, alternative splicing, and post-translational modifications. Methodological innovations advancing the field such as proteomic approaches and single cell expression studies are additionally described. Further, the chapter highlights the importance of choosing an appropriate brain region to analyze synaptic recognition factors and the advantages offered by laminated structures like the hippocampus or retina. In a concluding section, the profound disease relevance of aberrant synaptic recognition for neurodevelopmental and psychiatric disorders is discussed. Based on the current progress, an outlook is presented on research goals that can further advance insights into how recognition molecules provide for the astounding precision and diversity of synaptic connections.

The receptor protein tyrosine phosphatase CLR-1 is required for synaptic partner recognition

During neural circuit formation, most axons are guided to complex environments, coming into contact with multiple potential synaptic partners. However, it is critical that they recognize specific neurons with which to form synapses. Here, we utilize the split GFP-based marker Neuroligin-1 GFP Reconstitution Across Synaptic Partners (NLG-1 GRASP) to visualize specific synapses in live animals, and a circuit-specific behavioral assay to probe circuit function. We demonstrate that the receptor protein tyrosine phosphatase (RPTP) clr-1 is necessary for synaptic partner recognition (SPR) between the PHB sensory neurons and the AVA interneurons in C. elegans. Mutations in clr-1/RPTP result in reduced NLG-1 GRASP fluorescence and impaired behavioral output of the PHB circuit. Temperature-shift experiments demonstrate that clr-1/RPTP acts early in development, consistent with a role in SPR. Expression and cell-specific rescue experiments indicate that clr-1/RPTP functions in postsynaptic AVA neurons, and overexpression of clr-1/RPTP in AVA neurons is sufficient to direct additional PHB-AVA synaptogenesis. Genetic analysis reveals that clr-1/RPTP acts in the same pathway as the unc-6/Netrin ligand and the unc-40/DCC receptor, which act in AVA and PHB neurons, respectively. This study defines a new mechanism by which SPR is governed, and demonstrates that these three conserved families of molecules, with roles in neurological disorders and cancer, can act together to regulate communication between cells.

Detection of 16 gamma-ray pulsars through blind frequency searches using the Fermi LAT

Pulsars are rapidly rotating, highly magnetized neutron stars emitting radiation across the electromagnetic spectrum. Although there are more than 1800 known radio pulsars, until recently only seven were observed to pulse in gamma rays, and these were all discovered at other wavelengths. The Fermi Large Area Telescope (LAT) makes it possible to pinpoint neutron stars through their gamma-ray pulsations. We report the detection of 16 gamma-ray pulsars in blind frequency searches using the LAT. Most of these pulsars are coincident with previously unidentified gamma-ray sources, and many are associated with supernova remnants. Direct detection of gamma-ray pulsars enables studies of emission mechanisms, population statistics, and the energetics of pulsar wind nebulae and supernova remnants.

The Fermi Gamma-Ray Space Telescope discovers the pulsar in the young galactic supernova remnant CTA 1

Energetic young pulsars and expanding blast waves [supernova remnants (SNRs)] are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 milliseconds and a period derivative of 3.614 x 10(-13) seconds per second. Its characteristic age of 10(4) years is comparable to that estimated for the SNR. We speculate that most unidentified Galactic gamma-ray sources associated with star-forming regions and SNRs are such young pulsars.

Penetrating air gun wound in the neck

BACKGROUND

Injuries from air weapons can be serious and potentially fatal. It has been estimated that up to four million such weapons exist in UK households.

CASE REPORT

We present the case of an 8-year-old boy who sustained a penetrating neck wound from an air gun. Use of the flexible laryngoscope in the resuscitation room allowed localization of the gun pellet in the airway.

CONCLUSIONS

This approach, combined with careful clinical assessment led to immediate removal by direct laryngoscopy, thus avoiding the morbidity of unnecessary surgical exploration.

Cost and morbidity of MRSA in head and neck cancer patients: what are the consequences?

Methicillin resistant Staphylococcus aureus (MRSA) has become a prevalent nosocomial pathogen worldwide. The objectives of this study were to assess the morbidity and cost associated with the treatment of head and neck cancer patients who become colonized or infected with MRSA following major surgical procedures. We present a retrospective review of patients who underwent major surgery for head and neck cancer over a one year period and who then became MRSA positive in the post-operative period. MRSA affected 25/55 (45 per cent) patients who underwent major head and neck procedures during the period studied. The mean time of diagnosis was 13 days post-surgery. Morbidity included cellulitis, osteomyelitis and MRSA pneumonia. Thirteen of the patients who became MRSA positive (52 per cent of the MRSA group) required further surgery including plate removal, new flap formation and wound debridement as a result of the infection. Average in-hospital stay was almost three times more prolonged for patients who became MRSA positive compared to those who did not have MRSA. The costs of the first hospital stay were over three times more in the MRSA-positive group of patients. Antibiotic costs were increased by pound 2470 per patient because of MRSA. The extra stay in hospital, together with extra days in intensive care, extra medical and nursing care and additional costly antibiotic treatment, led to major cost implications and loss of health service resources in the unit. MRSA infection is a serious cause of morbidity in any surgical group of patients and this study focuses on the consequences for treatment of head and neck cancer patients in particular.

Management of a large bronchial haemangioma in an infant

Haemangiomas are the most common soft tissue tumor of infancy. Despite the benign and trivial nature of most cutaneous haemangiomas, airway haemangiomas are rare but potentially life threatening. We report the case of a 9-week-old infant with a left main stem bronchial haemangioma. This was successfully treated with the oral corticosteroids. We discuss the current available treatments for haemangiomas and highlight that treatment should be specific to each individual case.

Translevator anal anomalies with cutaneous fistulae passing deep to the scrotum

METHODS

The authors present a series of 9 patients collected from 4 centers with translevator anal anomalies, each of which has a fistula tracking forward deep to the scrotum and opening at the peno-scrotal junction. Whereas some would appear to be covered ani in type, others are deeper and would appear to fit in with an intermediate type of classification emphasizing the idea of a "spectrum" of malformation.

RESULTS

The anatomic arrangement, associated anomalies (eg, 2 had hypospadias), and surgical management is described briefly in each case. Careful examination may be necessary to identify the fistula.

CONCLUSIONS

It is recommended that the surgery be individualized depending on the findings. On a theoretical embryologic basis there is abnormality in the formation of the outer genital folds, and there also may be abnormality in some cases of the inner genital folds.

Reduction of glycemic and lipid levels in db/db diabetic mice by psyllium plant fiber

The soluble plant fiber psyllium significantly reduced fasting glucose and total cholesterol levels in the C57BL/KsJ db/db diabetic mouse relative to placebo-fed mice. Insulin levels were significantly higher in psyllium-fed than placebo-fed animals, indicating this fiber may delay the progression of diabetes in the animal model. High-density lipoprotein cholesterol levels rose moderately in both psyllium- and placebo-fed animals during the study, whereas triglyceride levels remained unchanged in both groups. Psyllium's effect on glycemic, lipid, and hormone parameters was not explained by weight loss or reduced food intake; these were similar in psyllium- and placebo-fed animals during the study. Our results show that psyllium fiber can beneficially moderate glycemic and lipid parameters in the db/db diabetes model.

Congenital leukonychia striata

Leukonychia striata of a unique appearance and distribution is described in a 51-year-old woman. Histopathologic examination of a specimen from the nail plate revealed a transverse band of parakeratosis on the ventral surface. Disturbance in keratinization on the nail plate is presumed to be secondary to abnormalities in the nail matrix. We review briefly the classification and pathogenesis of leukonychia, an interesting aberration in nail plate keratinization.

Clinical trial of cefuroxime axetil in children

Cefuroxime axetil tablets were given to 12 children (aged 19 months to 13.5 years) for a total of 14 episodes of lower respiratory tract infection. Doses ranged from 15 to 32 mg/kg/day. Six infections were regarded as cured and seven improved. In four cases, Haemophilus influenzae was present at the end of treatment. Serum levels of cefuroxime showed great variability. Absorption and penetration of the drug into the lower respiratory mucosa may not be sufficient to kill organisms which are sensitive in vitro. Cefuroxime axetil tablets were acceptable to most children.

Pigmentation induced by quinidine therapy

Abnormalities of pigmentation are a well-known side effect of antimalarial therapy. Quinidine, an antiarrhythmic agent, is structurally related to the common antimalarials but, to our knowledge, has not been associated with pigmentary abnormalities. We report a case of localized blue-gray pigmentation, clinically and histologically identical to antimalarial-induced pigmentation, in a patient receiving quinidine therapy.

Manipulation of platelet aggregation by prostaglandins and their fatty acid precursors: pharmacological basis for a therapeutic approach

Addition of the one-, two- or three- series endoperoxide to human platelet-rich plasma tend to suppress aggregation, through the action of their respective non-enzymatic breakdown products PGE1, PGD2, or PGD3 all of which elevate cyclic AMP levels. On the other hand, these stable primary products do not arise in appreciable amounts from intrinsic endoperoxides generated from either endogenous or exogenous free fatty acids. 5,8,11,14,17-Eicosapentaenoic acid (EPA) suppresses arachidonic acid (5,8,11,14-eicosatetraenoic acid) conversion by cyclooxygenase (as well as lipoxygenase) to aggregatory metabolites in platelets. Exogenously added EPA was capable of inhibiting PRP aggregation induced either by exogenous or endogenous (released by ADP or collagen) arachidonate. The hypothetical combination of an EPA-rich diet and a thromboxane synthetase inhibitor might abolish production of the pro-aggregatory species, thromboxane A2, and enhance formation of the anti-aggregatory metabolite, prostacyclin. Whereas EPA is not detectably metabolized by platelets, dihomo-gamma-linolenic acid (8,11,14-eicosatrienoic acid) is primarily converted by cyclooxygenase and thromboxane synthetase into the inactive metabolite, 12-hydroxyheptadecadienoic (HHD) acid. Pretreatment of human platelet suspensions with the thromboxane synthetase inhibitor imidazole unmasks the aggregatory property of PGH1 and DLL which was partially compromised by the PGE1 formed. The combination of the thromboxane synthetase inhibitor and an adenylate cyclase inhibitor unmasks a complete irreversible aggregation by DLL or PGH1. The basis of a dietary strategy that replaces AA with DLL must rely on the production by the platelet of an inactive metabolite (HHD) rather than thromboxane A2.

Vitamin C metabolism and atopic allergy

The procedure for carrying out the Leucocyte Ascorbic Acid Uptake Direct Antigen Challenge Test (LAADACT) is described. Leucocytes from normal individuals, when incubated in a buffered medium containing ascorbic acid, increase their ascorbic acid concentration by about 80%. When leucocytes from atopic individuals are incubated in a medium containing the antigen to which they are sensitive, as shown by positive skin tests, the leucocyte uptake of ascorbic acid is significantly reduced. Addition of antigen, to which atopic or normal individuals are not sensitive, to the incubation mixture does not reduce leucocyte ascorbic acid uptake. Measurement of ascorbic acid uptake into leucocytes is a relatively simple, routine, laboratory procedure. The LAADACT, therefore, provides a quick and accurate blood test for diagnosing sensitivity to specific antigens, and measuring relative antigenic sensitivities. The underlying mechanism of the LAADACT is discussed.